The test is a smoke opacity
measurement for in-use motor vehicles equipped with
compression-ignition
(diesel) engines, using the free acceleration from low idle speed
method.

2. Motor Vehicle Test Condition

a. The test
shall
be carried out on a stationary vehicle and the engine shall be first
brought
to normal operating conditions during a road run or dynamic test. In
particular,
cooling water and oil should be at normal temperature.

b. The combustion
chamber
should not have been cooled or fouled due to a prolonged period of
idling
preceding the test.

c. The exhaust system
shall
not have any orifice or leaks wherein the gases emitted by the engine
might
be diluted.

a. Follow the
opacimeter
manufacturer's instruction for on the proper installation,
operation/use
and checking the accuracy and calibration before and after each test.

b. Set the vehicle
gear-change
control in the neutral position and the hand-brake effectively engaged.

c. Start the engine
and warm
it up to its normal operating temperature.

d. Accelerate the
engine
two to three times (2-3) prior to smoke sampling in order to remove
deposits
of soot and other carbon particles in the tail pipe.

e. With the engine
idling,
depress the accelerator quickly, but not violently, to obtain maximum
delivery
from the injection pump. Maintain this position until maximum engine
speed
is reached for about two (2) to four (4) seconds and the governor comes
into action. As soon as this speed is reached, release the accelerator
until the engine resumes its idling speed. Record the maximum reading
of
the smokemeter.

f. The operation
described
in paragraph (4)(e) shall be repeated not less than six (6) times in
order
to clear the exhaust system and to allow for any necessary adjustment
of
the apparatus. The maximum opacity values read in each successive
acceleration
shall be noted until stabilized values are obtained. The values read
shall
be regarded as stabilized when four (4) consecutive readings are within
a hand width of 0.25 m-1 and do not form a decreasing sequence. The
arithmetic
mean of the four stabilized values shall be the test result for the
concerned
vehicle.

g. For motor vehicles
designed
with several exhaust outlets that are individually connected from
paired
exhaust ports, the free acceleration test shall be carried out on each
outlet. In this case, the values used for calculating the correction to
the absorption coefficient shall be arithmetical mean values recorded
at
each outlet and the test shall be valid only if the extreme values
measured
do not differ by more than 0.15m-1 For motor vehicles designed with
several
exhaust outlets connected from one exhaust pipe coming from the
engine's
exhaust manifold collector, the free acceleration test shall be carried
out only on one exhaust outlet, the other outlets effectively blocked
to
prevent leaks.

h. Seal the full load
screw
of the injection pump/delivery system of the motor vehicle after a
pass-test
to prevent tampering.